Aspiration system and method

ABSTRACT

Aspiration catheters and methods for the treatment of an occlusion in a blood vessel. These catheters and methods are especially useful in the removal of occlusions from saphenous vein grafts, the coronary and carotid arteries, arteries above the aortic arch and even smaller vessels. The catheters of the present invention are provided in either over-the-wire or in single operator form. Radiopaque markers are preferably incorporated into distal ends of the catheters, and visual markers are incorporated into the proximal end of the catheters, to facilitate their positioning within the body. The catheters are provided with varying flexibility along the length of the shaft, such that they are soft and flexible enough to be navigated through the vasculature of a patient without causing damage, but are stiff enough to sustain the axial push required to position the catheter properly and to sustain the aspiration pressures. Support mandrels and support sheaths may also be added to impart additional strength to the length of the catheter.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.09/026,013, filed Feb. 19, 1998, now U.S. Pat. No. 6,152,909, which is acontinuation-in-part of U.S. application Ser. No. 08/813,808, filed Mar.6, 1997, abandoned, and U.S. application Ser. No. 08/813,807, filed Mar.6, 1997, abandoned, and U.S. application Ser. No. 08/812,875, filed Mar.6, 1997, now U.S. Pat. No. 5,833,644, which is a continuation in part ofU.S. application Ser. No. 8/650,464 filed May 20, 1996, abandoned, allof which are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to aspiration catheters for aspiratingemboli, thrombi, and other types of particles from the vasculature of apatient, the apparatus being particularly well suited for aspirationwithin saphenous vein grafts, coronary arteries, and similar vessels.

2. Description of the Related Art

Human blood vessels often become occluded or completely blocked byplaque, thrombi, other deposits, emboli or other substances, whichreduce the blood carrying capacity of the vessel. Should the blockageoccur at a critical place in the circulatory system, serious andpermanent injury, or even death, can occur. To prevent this, some formof medical intervention is usually performed when significant occlusionis detected.

Coronary heart disease is an extremely common disorder in developedcountries, and is the leading cause of death in the U.S. Damage to ormalfunction of the heart is caused by narrowing or blockage of thecoronary arteries (atherosclerosis) that supply blood to the heart. Thecoronary arteries are first narrowed and may eventually be completelyblocked by plaque, and may further be complicated by the formation ofthrombi (blood clots) on the roughened surfaces of the plaques.Myocardial infarction can result from atherosclerosis, especially froman occlusive or near occlusive thrombi overlying or adjacent to theatherosclerotic plaque, leading to death of portions of the heartmuscle. Thrombi and emboli also often result from myocardial infarction,and these clots can block the coronary arteries, or can migrate furtherdownstream, causing additional complications.

Various types of intervention techniques have been developed whichfacilitate the reduction or removal of the blockage in the blood vessel,allowing increased blood flow through the vessel. One technique fortreating stenosis or occlusion of a blood vessel is balloon angioplasty.A balloon catheter is inserted into the narrowed or blocked area, andthe balloon is inflated to expand the constricted area. In many cases,near normal blood flow is restored. It can be difficult, however, totreat plaque deposits and thrombi in the coronary arteries, because thecoronary arteries are small, which makes accessing them with commonlyused catheters difficult.

Other types of intervention include atherectomy, deployment of stents,introduction of specific medication by infusion, and bypass surgery.Each of these methods are not without the risk of embolism caused by thedislodgement of the blocking material which then moves downstream. Inaddition, the size of the blocked vessel may limit percutaneous accessto the vessel.

In coronary bypass surgery, a more costly and invasive form ofintervention, a section of a vein, usually the saphenous vein taken fromthe leg, is used to form a connection between the aorta and the coronaryartery distal to the obstruction. Over time, however, the saphenous veingraft may itself become diseased, stenosed, or occluded, similar to thebypassed vessel. Atherosclerotic plaque in saphenous vein grafts tendsto be more friable and less fibrocalcific than its counterpart in nativecoronary arteries.

Diffusely diseased old saphenous vein grafts with friableatherosclerotic lesions and thrombi have therefore been associated withiatrogenic distal embolic debris. Balloon dilatation of saphenous veingrafts is more likely to produce symptomatic embolization thandilatation of the coronary arteries, not only because of the differencein the plaque but also because vein grafts and their atheromatousplaques are generally larger than the coronary arteries to which theyare anastomosed. Once the plaque and thrombi are dislodged from thevein, they can move downstream, completely blocking another portion ofthe coronary artery and causing myocardial infarction. In fact, coronaryembolization as a complication of balloon angioplasty of saphenous veingrafts is higher than that in balloon angioplasty of native coronaryarteries. Therefore, balloon angioplasty of vein grafts is performedwith the realization that involvement by friable atherosclerosis islikely and that atheroembolization represents a significant risk.

Because of these complications and high recurrence rates, old diffuselydiseased saphenous vein grafts have been considered contraindicationsfor angioplasty and atherectomy, severely limiting the options forminimally invasive treatment. However, some diffusely diseased oroccluded saphenous vein grafts may be associated with acute ischemicsyndromes, necessitating some form of intervention.

There is therefore a need for improved methods of treatment for occludedvessels such as saphenous vein grafts and the smaller coronary arterieswhich decrease the risks to the patient.

SUMMARY OF THE INVENTION

The present invention provides novel aspiration catheters for removingplaque, thrombi, emboli, and other types of obstructions from bloodvessels. The present invention advantageously satisfies the need in theprior art by providing a catheter adapted to be compactly utilized ineven the smaller size blood vessels. It can also be easily adapted toprovide efficient and speedy evacuation in larger size vessels. Thissystem is compatible with more common therapy devices in widespread usetoday, and is designed for rapid evacuation and ease of use.

The catheters of the present invention are provided in eitherover-the-wire or in single operator form. The catheters are sized so asto be used in very small blood vessels. Radiopaque markers arepreferably incorporated into the distal ends of the catheters tofacilitate their positioning within the body; similarly, a marker may beplaced on the proximal end of the catheter to aid in the insertion ofthe catheter in to the patient. The catheters are provided with varyingflexibility along the length of the shaft, such that they are soft andflexible enough to be navigated through the vasculature of a patientwithout causing damage, but are stiff enough to sustain the axial pushrequired to position the catheter properly and to sustain the aspirationpressures. A support mandrel may be incorporated into the catheter toprovide additional strength, A support sheath is preferably included toprevent crushing of the aspiration lumen when the catheter is used inconjunction with valves, adaptors or other fittings.

The catheters are preferably sized so as to allow the slidable insertionof a therapy catheter through the main aspiration lumen of theaspiration catheter. Alternatively, the therapy catheter can be builtover the aspiration catheter. In either case, the aspiration and therapycatheters can be delivered simultaneously, saving valuable time duringthe procedure.

One embodiment of the aspiration catheter of the present inventiontherefore comprises an elongate flexible tubular body having a proximalend and a distal end. The catheter body or shaft incorporates areinforcement such as a metallic braid or coil or a polymer coil toprovide strength and flexibility to the device. A main lumen extends thelength of the tubular body, and an aspiration port at the proximal endof the catheter body is in fluid communication with the main lumen, suchthat aspiration pressure can be provided through the port and mainlumen. The distal tip on the catheter is formed of a more flexiblematerial than that used to form the rest of the catheter shaft. Markersare preferably incorporated in to both the distal and proximal ends ofthe catheter to assist in positioning the catheter in the patient.

The reinforcement can be formed from a variety of materials, includingpolymers, stainless steel, silver or gold plated stainless steel,ELGILOY, platinum, nitinol, or a combination thereof. The distal end ofthe catheter body is preferably more flexible than the proximal end, andthis can be achieved by providing a braid or coil density at the distalend which is greater an the braid or coil density at the proximal end.At least one support mandrel may be used to provide the catheter withadditional strength.

The catheter's main lumen is preferably sized to receive at least oneseparate catheter, such as a therapy catheter, which is slidablydisposed herein. The inner diameter of the main lumen is preferablyabout 0.045.″

The aspiration catheter of the present invention can include a secondlumen adjacent the main lumen which is adapted to receive a guidewiretherethrough. The second lumen can extend substantially the entirelength of the tubular body, or can extend less than 40 cm or less than20 cm in a proximal direction from the distal end of the body. Thesecond lumen can contain a slit through a side wall to allow insertionand removal of the guidewire therethrough. In a preferred embodiment,the second lumen has an inner diameter of approximately 0.020″ toreceive a 0.014″ diameter guidewire.

The distal tip of the catheter can have at least one side port tofacilitate aspiration. The distal tip can be tapered, blunt, or angledto create an oblique opening. The catheter preferably also comprises avalve in fluid communication with the main lumen, to control theapplication of aspiration pressure at the distal end of the device. Theaspiration catheter of the present invention can also incorporatevarious coatings, such as hydrophilic or hydrophobic coatings,antithrombogenic coatings, or a combination thereof.

In another embodiment of the present invention, the aspiration cathetercomprises an elongate flexible tubular body having a proximal end and adistal end, a main lumen extending through the tubular body sized toreceive at least one separate catheter which is slidably disposedtherein, an aspiration port at the proximal end of the tubular body, theaspiration port being in fluid communication with the main lumen, and atip on the distal end of the tubular body, the tip being formed of amore flexible material than that used to form the tubular body. Again,the catheter can have a second lumen adjacent the first adapted toreceive a guidewire therethrough, a specially shaped distal tip, and anoptional valve in fluid communication with the main lumen.

In yet another embodiment of the present invention, the aspirationcatheter comprises an elongate flexible tubular body having a proximalend and a distal end, a main aspiration lumen through the tubular body,an aspiration port on the proximal end of the tubular body in fluidcommunication with the main lumen, a therapeutic device attached to thedistal end of the tubular body, and a tip on the distal end of thetubular body formed of a more flexible material than that used to formthe tubular body itself. The therapeutic device can be an inflatableballoon and the catheter can include a separate inflation lumen for theballoon adjacent the main lumen.

The aspiration catheter may be part of an aspiration system whichcomprises the aspiration catheter, an extension line having a valve orstopcock to control the delivery of the aspiration pressure, and asource of negative pressure such as a syringe.

Accordingly, the catheters of the present invention provide for veryfast and efficient aspiration of the working area surrounding theocclusion in a blood vessel. The catheters can be utilized in a widerange of vessel diameters, including extremely small ones, are easy touse and can quickly and efficiently evacuate occlusions and debris,allowing the physician to restore normal blood flow in these vessels ina very short period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a human heart showing a saphenous veingraft used to bypass a portion of the coronary arteries.

FIG. 2 is a side view of an over-the-wire aspiration catheter inaccordance with the present invention.

FIG. 3 is a cross section of the aspiration catheter of FIG. 2, takenalong line 3—3 in FIG. 2.

FIG. 4 is a cross section of the aspiration catheter of FIG. 2 showing aguide wire over which the aspiration catheter rides.

FIG. 5 is a side view of a single operator type aspiration catheter inaccordance with the present invention.

FIG. 6 is a cross section of the proximal end of the aspiration catheterof FIG. 5, taken along line 6—6 of FIG. 5.

FIG. 7A is a cross section of one embodiment of the distal end of theaspiration catheter of FIG. 5, taken along line 7—7 of FIG. 5.

FIG. 7B is a cross section of another embodiment of the distal end ofthe aspiration catheter of FIG. 5, also taken along line 7—7 of FIG. 5,showing a slit in the outer wall of the guidewire lumen through whichthe guidewire can be inserted and removed.

FIGS. 8A-C are side views of the various embodiments of the distal endof the aspiration catheter of the present invention.

FIG. 9 is a perspective view of an over-the-wire aspiration catheter andguidewire inserted into a saphenous vein graft in accordance with thepresent invention, with the vein graft shown partially cut away.

FIG. 10 is a schematic view of an occlusion catheter apparatus for usein the method of the present invention;

FIG. 11 is a schematic cross-sectional view of a distal portion of thecatheter apparatus shown in FIG. 10.

FIG. 12 is a perspective view of a valve which can be positioned at theproximal end of the catheter of the present invention to controlaspiration.

FIG. 13 is a side view of another embodiment of the over-the-wireaspiration catheter.

FIG. 14 is a cross-sectional view of the aspiration catheter of FIG. 13,taken along line 14—14 in FIG. 13.

FIG. 15 is a side view of another embodiment of the single operator typeaspiration catheter.

FIG. 16 is a cross-sectional view of the aspiration catheter of FIG. 15,taken along line 16—16 in FIG. 15.

FIG. 17 is a side view of an aspiration system, which includes anaspiration catheter, an extension line having a stopcock, and a sourceof aspiration pressure.

FIG. 18 is a perspective view of an over-the-wire aspiration catheterhaving an occlusive balloon on its distal end and guidewire insertedinto a saphenous vein graft in accordance with the present invention,with the vein graft shown partially cut away.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides novel aspiration catheters for aspiratingemboli, plaque, thrombi or other occlusions from a blood vessel andmethods of using same. The present invention is adapted for use in thetreatment and removal of an occlusion in a blood vessel in which theocclusion has a length and a width or thickness which at least partiallyoccludes the vessel's lumen. Thus, the catheters of the presentinvention are effective in treating both partial and complete occlusionsof the blood vessels. As used herein, “occlusion” includes both partialand complete occlusions, stenoses, emboli, thrombi, plaque and any othersubstance which at least partially occludes the vessel's lumen.

The method of the present invention can be used to provide aspirationwith or without the need for a separate irrigation catheter andirrigation fluid. In the context of removing plaque, thrombi or otherblockages from blood vessels, it has heretofore been proposed that anisolated “chamber ” surrounding the occlusion be created prior toattempting treatment, and that separate irrigation fluid be providedthrough an irrigation catheter to the chamber. It has been discoveredthat isolation of the occlusion is not required in some cases, and thatthe occlusion can be successfully removed through therapy and/oraspirating of the resulting debris without the need for delivery of aseparate irrigation catheter and irrigation fluid in those vessels wherecertain pressure and fluid flow conditions exist, such as saphenous veingrafts, coronary arteries, carotid arteries and similar vessels.

In non-bifurcated areas of the blood vessels, it has been discoveredthat fluid from the proximal portion of the same vessel acts as aninfusion source. One can therefore occlude only the distal portion ofthe vessel to create a working area surrounding the occlusion and allowblood to flow from the proximal portion of the vessel into the workingarea. The working area surrounding the occlusion is aspirated throughthe guiding catheter or aspiration catheter. It should be noted that, asused herein, “proximal ” refers to the portion of the apparatus closestto the end which remains outside the patient's body, and “distal ”refers to the portion closest to the end inserted into the patient'sbody.

The method and apparatus of the present invention can be used in anyvessel of the body where the pressure is at least 0.2 psi, andpreferably, is about 1.2 psi, with a flow rate of at least 10 cc perminute. The method and apparatus are particularly suited for use inremoval of occlusions from saphenous vein grafts, coronary and carotidarteries, and in other non-branching vessels having similar pressuresand flow where a suitable working area can be created. A saphenous veingraft is depicted in FIG. 1. The graft 2 is used to bypass one of theoccluded coronary arteries 4, and connects the aorta 6 to the coronaryartery at a location distal the occlusion 8. Although the presentinvention will be described in connection with a saphenous vein graft,it should be understood that this application is merely exemplary, andthe method can be used in other blood vessels as well.

Apparatus Used With the Present Invention

1. Guide Catheter and Occlusion Catheter

To perform the method of the present invention, a guide catheter havinga single lumen is first introduced into the patient's vasculaturethrough an incision made in the femoral artery in the groin and used toguide the insertion of other catheters and devices to the desired site.Following insertion of the guide catheter, a second catheter is insertedthrough the guide catheter and past the site of the occlusion. Thecatheter has an occlusive device, such as an inflatable balloon, filteror other mechanical occlusive device, attached at its distal end. Theocclusive device should be capable of preventing the migration ofparticles and debris from the working area, either through total orpartial occlusion of the vessel. Note that the occlusion of the vesselneed not be complete. Substantial occlusion of the vessel can besufficient for purposes of the present invention. The catheter should besized so as to be slidable with respect to the therapy and aspirationcatheters inserted over the catheter. The catheter is preferably made ofmetal such as stainless steel or nitinol, plastics, or composites. Aguidewire having an occlusive device on its distal end is also suitablefor use in the present method. The method of the present invention canbe effectively carried out using a number of guidewires or cathetersthat perform the function of occluding the vessel and allowing for theslidable insertion of various other catheters and devices. The term“catheter ” as used herein is therefore intended to include bothguidewires and catheters with these desired characteristics.

A catheter suitable for use in the present invention is illustrated inFIGS. 10 and 11. The catheter apparatus 110 is generally comprised offour communicating members including an elongated tubular member 114, aninflatable balloon member 116, a core-wire member 120 and a coil member122. The catheter apparatus 110 is preferably provided with an outercoating of a lubricious material, such as Teflon.

The body member 114 of the catheter apparatus 110 is in the form ofhypotubing and is provided with proximal and distal ends 114A and 114Bas well as an inner lumen 115 extending along the tubular member 114.The balloon member 116 is coaxially mounted near the distal end 114B ofthe tubular member 114 by suitable adhesives 119 at a proximal end 116Aand a distal end 116B of the balloon member 116 as shown in FIG. 11.Proximal and distal tapered portions 123A and 123B on either side of theballoon 116 preferably include adhesives. Proximal and distal adhesivestops 125 and 126 contact the adhesives 119 to define the working lengthof the balloon 116. A radiopaque marker 127 is preferably located withinthe proximal tapered portion 123A. A notch 128 in the tubular member 114permits fluid communication between the lumen 115 and the balloon 116.

A core-wire member 120 of the catheter 110 may be comprised of aflexible wire. The flexible wire 120 is preferably secured to thetubular member 114 within the lumen 115 by a combination of adhesivesand crimps 129 (FIG. 11). The proximal end 120A of the flexible wire 120can have a transverse cross sectional area substantially less than thesmallest transverse cross-sectional area of the inner lumen 115 of thetubular member 114. The flexible wire 120 can also taper towards thedistal end 120B to smaller diameters to provide greater flexibility tothe flexible wire 120. However, the flexible wire 120 may be in the formof a solid rod, ribbon or a helical coil or wire or combinationsthereof. As shown in FIG. 11, the distal end 120B of the flexible wire120 is secured to a rounded plug 118 of solder or braze at the distalend 122B of the coil member 122. The coil member 122 of the catheter 110may be comprised of a helical coil. The coil member 122 is coaxiallydisposed about the flexible wire 120, and is secured to the flexiblewire 120 by soldering or brazing.

The balloon member 116 is preferably a compliant balloon formed of asuitable elastic material such as a latex or the like. The flexible coil122 is preferably formed of a wire of platinum or gold based alloys. Theflexible core-wire 120 and the tubular member 114 are preferably formedof a superelastic nickel-titanium alloy.

The catheters of the present invention are preferably provided with acoating on the outer surface, or on both the inner and outer surfaces.Suitable coatings include hydrophilic, hydrophobic and antithrombogeniccoatings. Examples include heparin, silicone, polyurethane and PVP.These coatings can be applied using methods well known in the art.

Additional details relative to the catheters described above are foundin copending U.S. patent applications Ser. No. 08/813,023, filed Mar. 6,1997, now U.S. Pat. No. 6,270,477, Ser. No. 08/812,876, filed Mar. 6,1997, now U.S. Pat. No. 6,068,623, entitled “Catheter for EmboliContainment System” and “Hollow Medical Wires and Methods ofConstructing Same”, respectively, and U.S. patent applications Ser. No.09/026,225, filed Feb. 19, 1998, Ser. No. 09/026,357, filed Feb. 19,1998, now U.S. Pat. No. 6,190,332, and Ser. No. 09/026,105, filed Feb.19, 1998, now U.S. Pat. No. 6,228,072, entitled “Balloon Catheter andMethod of Manufacture”, “Core Wire With Shapeable Tip”, and “Shaft forMedical Catheters”, respectively, all of which are hereby incorporatedby reference in their entirety.

2. Therapy Catheter

Once the guiding catheter and second catheter have been properlypositioned inside the vessel, the occlusive device at the distal end ofthe catheter is actuated to occlude the vessel distal to the existingocclusion to create a working area. A therapy catheter then is deliveredto the site of the occlusion. The term “therapy catheter ” is meant toinclude any of a number of known devices used to treat an occludedvessel. For example, a catheter carrying an inflatable balloon for usein balloon angioplasty can be delivered to dilate the occlusion. Thermalballoon angioplasty includes the use of heat to “mold ” the vessel tothe size and shape of the angioplasty balloon. Similarly, anintravascular stent can be delivered via a balloon catheter and deployedat the site of the occlusion to keep the vessel open. Cutting, shaving,scraping or pulverizing devices can be delivered to excise the occlusionin a procedure known as atherectomy. A laser or ultrasound device canalso be delivered and used to ablate plaque in the vessel. Variousthrombolytic or other types of drugs can be delivered locally in highconcentrations to the site of the occlusion. It is also possible todeliver various chemical substances or enzymes via a catheter to thesite of the stenosis to dissolve the obstruction. The term “therapycatheter ” encompasses these and similar devices.

3. Aspiration Catheter

After the therapy has been performed and the stenosis has been removedor reduced using any of the methods and apparatus described above, theworking area is aspirated to remove fluid and debris. Aspirationpressure can be provided through the guide catheter if desired. A sourceof negative pressure is attached at the proximal end of the guidecatheter to create reverse flow, and fluid and debris are aspiratedthrough the guide catheter's main lumen.

Alternatively, an aspiration catheter or similar debris removing deviceis delivered to the working area to remove particles and any otherdebris. The term “aspiration catheter ” includes any device whichcreates an area of fluid turbulence and uses negative pressure andreverse flow to aspirate fluid and debris, and includes those deviceswhich create a venturi effect within the vessel. It should be noted thatany particles which break free during therapy and aspiration procedureswill be kept at the site of the procedure within the working area by theocclusive device occluding the distal portion of the vessel incombination with the blood pressure coming from the proximal portion ofthe vessel. The debris is prevented from migrating elsewhere, andremains localized for removal by aspiration.

An aspiration catheter particularly suited for use in the treatment andremoval of occlusions in blood vessels is illustrated in FIG. 2. Thecatheter 10 includes an adaptor 14, preferably a female luer adaptor,and a seal 16 at its proximal end. The catheter 10 further includes anaspiration port 18 to which a source of negative pressure is attached.The aspiration catheter further comprises a long tubular body 20 havinga distal end 22. The distal tip 22 can include a radiopaque marker toaid in locating the tip 22 during insertion into the patient, and ispreferably soft to prevent damage to the patient's vasculature. Theaspiration catheter is preferably about 145 cm in length, although thislength can be varied as desired.

The aspiration catheter illustrated in FIG. 2 is an over-the-wirecatheter. As seen in FIG. 3, the catheter body 20 is hollow, with aninternal diameter ranging from about 0.030″ to about 0.070″. Preferably,the inner diameter is about 0.045″. During insertion of the aspirationcatheter 10, the proximal end of a guidewire 26 is inserted into thedistal end of the aspiration catheter 22, and the aspiration catheter 10is slidably advanced over the guidewire 26, which is positioned insidethe hollow lumen 24 of the aspiration catheter 10. The position of theguidewire 26 relative to the body 20 of the aspiration catheter 10 isillustrated in FIG. 4, but of course can vary. For this type ofaspiration catheter 10, a very long guidewire 26, generally around 300cmin length, is used to facilitate the insertion of the aspirationcatheter 10 over the guidewire 26.

Alternatively, the aspiration catheter 30 can be of a single operatordesign, as illustrated in FIGS. 5-7. The catheter 30 has an adaptor 32and an aspiration port 34 at its proximal end. Like the over-the-wireaspiration catheter 10, the single operator aspiration catheter 30further comprises a long tubular body 36 having a distal end 38. Thedistal tip 38 can include a radiopaque marker to aid in locating the tip38 during insertion into the patient, and is preferably soft to preventdamage to the patient's vasculature. At the distal end of the shaft 38,a guidewire lumen 40 is attached. This lumen 40 provides a separatelumen, apart from the main aspiration lumen 42 of the catheter 30, forthe insertion of the guidewire 26. The inner diameter of the guidewirelumen ranges from about 0.016″ to about 0.020″ for use with a 0.014″guidewire system. In a preferred embodiment, the inner diameter of thelumen is about 0.019″. This guidewire lumen can be less than 10 cm inlength, but can extend 30 cm or longer in a proximal direction. Asillustrated in FIG. 7, during delivery of the aspiration catheter 30,the proximal end of the guidewire 26 is inserted into the distal end ofthe guidewire lumen 40, and the guidewire lumen 40 is slidably advancedover the guidewire 26. Unlike the over-the-wire catheter 10 describedabove, only a short segment of the single operator aspiration catheter30 rides over the guidewire 26, and the guidewire 26 remains in theguidewire lumen 40 and does not enter the aspiration lumen 42 of theaspiration catheter 30. With the single operator system 30, the longguidewire 26 used with the over-the-wire catheter 10, and the extraoperator needed to handle it, are not required.

Although the guidewire lumen 40 is shown in FIG. 5 as being located onlyon the distal end 38 of the shaft of the aspiration catheter 36, thelumen 40 can also be made to extend the entire length of the shaft 36 ifdesired. In both embodiments, the aspiration lumen 42 is advantageouslyleft completely unobstructed to provide more efficient aspiration. Theguidewire lumen 40 can also include a slit 41 along the entire length inthe outside wall of the lumen as shown in FIG. 7B to facilitate fasterand easier insertion and removal of the guidewire 26 through the sidewall of the lumen. By inserting and removing the guidewire through theside wall of the aspiration catheter, the need to remove adapters andattachments from the proximal end prior to slidably advancing orremoving the aspiration catheter over the guidewire is eliminated.

In both the over-the-wire and single operator type aspiration catheters,the elongate catheter shaft must have sufficient structural integrity,or “stiffness,” to permit the catheter to be pushed through thevasculature to distal arterial locations without buckling or undesirablebending of the body. It is also desirable, however, for the body to befairly flexible near its distal end, so that the tubular body may benavigated through tortuous blood vessel networks. Thus, in one preferredembodiment, the tubular body of the aspiration catheter is formed from apolymer such as polyethylene or PEBAX (Atochem, France) made to havevariable stiffness along its length, with the proximal portion of thetubular body being less flexible than the distal portion of the body.Advantageously, a tubular body of this construction enables a user tomore easily insert the tubular body into vascular networks difficult toaccess using conventional catheters of uniform stiffness. This isbecause the stiffer proximal portion provides the requisite structuralintegrity needed to advance the catheter without buckling, while themore flexible distal region is more easily advanced into and throughtortuous blood vessel passageways.

In one preferred embodiment, variable stiffness along the length of thecatheter shaft is achieved by forming a polymeric tubular body whichincorporates a reinforcement along its length. For example, the tubularbody may be provided with a reinforcing braid or coil incorporated intoits wall structure. The reinforcement can be formed of metal or ofvarious polymers. To achieve variable stiffness, the distal region ofthe catheter is provided with a braid or coil having a higher braid orcoil density than that present in the braid or coil of the proximalregion. The lower braid density in the proximal region makes it lessflexible, or “stiffer”, than the distal region of the catheter.

The precise density of the braiding or coiling provided to the proximal,distal and transition regions can be varied considerably at the time ofmanufacture, such that catheters having a variety of differentflexibility profiles may be created. Moreover, the braid or coil densitymay be varied within the catheter regions as well, by providing a braidor coil which has a braid or coil density gradient along its length. Forexample, the most proximal part of the proximal region may be providedwith a metallic braid having a braid density of about 50-90 picks perinch, with the braid density increasing at a rate of about 2-5 picks perinch as the braid extends in the distal direction. This reinforcedconstruction of the catheter provides adequate proximal stiffness foraxial push, while preventing collapse of the distal tip duringaspiration.

A variety of different materials, known to be ductile and shapeable intofine wires, may be used to form the reinforcement. For example, variouspolymers, stainless steel, silver or gold plated stainless steel,platinum, nitinol, or a combination thereof are suitable. In onepreferred embodiment, the braid is formed of stainless steel, and has abraid density which varies from 50-70 picks per inch at the mostproximal part of the proximal region of the catheter, to 80-100 picksper inch at the most distal part of the distal region of the catheter.

Reinforcing braids or coils may be introduced into the structure of thecatheter body through conventional catheter forming techniques. Forexample, the tubular body may be formed by inserting a 72D PEBAX tubeinto a variable braid density stainless steel sleeve, and then insertingthe sleeved tube into a 72D PEBAX outer tube of the same length, so thatthe braided sleeve is sandwiched between the two tubes. A shapingmandrel may be inserted within the inner PEBAX tube, and shapingcontainer over the outer PEBAX tube, and the entire apparatus may thenbe placed in a hot box kept at a temperature slightly greater than themelting temperature of the PEBAX tubes. The PEBAX tubes will melt andfuse together, and once cooled, will form a tubular body incorporatingthe braid. This same technique can be used to form a tubular bodyincorporating a coil.

In another embodiment, variable stiffness of the tubular body may beachieved by forming the proximal and distal regions of the tubular bodyout of polymeric materials having differing degrees of stiffness. Forexample, one half of an inner tube of 72D PEBAX may be inserted into anouter tube of 40D PEBAX, and the other half of the inner tube may beinserted into a 72D PEBAX outer tube. The combination may then be heatfused, as described above. The 40D/72D PEBAX combination forms a moreflexible tubular body than the region of the 72D/72D PEBAX combination.More or less flexible materials may be used as desired to alter theflexibility of the resulting tubular body. Furthermore, the flexibilityof the various regions of a tubular body formed in this manner may bevaried further by incorporating a braid or coil having either a uniformbraid density or coil pitch, or a varying density or coil, into thetubular body, as described above.

Moreover, any of a variety of different polymeric materials known bythose of skill in the art to be suitable for catheter body manufacturemay be used to form the catheter body. For example, the body may beformed out of polymers such as polyethylene, PEBAX, polyimide, polyetheretherketone, and the like. Different materials might also be combined toselect for desirable flexibility properties.

Also, although the catheter body has been described in the context ofhaving two regions of differing flexibility, it will be readilyappreciated by those of skill in the art that three or more regions ofdiffering flexibility may easily be provided, by adapting the teachingscontained herein.

A further embodiment of the aspiration catheter includes at least onesupport mandrel incorporated in to the catheter body to furtherstrengthen the catheter. One such catheter having two support mandrelsis illustrated in FIG. 13. This over-the-wire aspiration catheter 210 isapproximately 135-140 cm in length, and includes two lumens, anaspiration lumen 212 and a separate guidewire lumen 214. Both lumens212, 214 extend from the proximal end of the catheter 218 to the distalend 220. As explained above, the catheter 210 preferably includes anadaptor 211 at its proximal end 218. The adaptor 211 it connects to asource of negative pressure to provide aspiration through the aspirationlumen 212. During insertion of the aspiration catheter 210, the catheter210 is slidably advanced over a guidewire positioned within theguidewire lumen 214, as described above.

As illustrated in FIG. 14, the aspiration and guidewire lumens 212, 214are adjacent one another. Two support mandrels 216 a, 216 b arepositioned alongside the lumens 212, 214 to provide added stiffness tothe length of the catheter body 210.

The mandrels 216 a, 216 b are preferably formed of stainless steel, butcould be made of any material which would provide additional strength tothe catheter body. The outer diameter of the mandrel is preferably nomore the 0.010″, to maintain the low profile of the catheter body 210.The mandrels 216 a, 216 b extend from the proximal end of the catheterbody 218, ending approximately 35 cm from the distal end of the catheter220.

The mandrels 216 a, 216 b are positioned adjacent the dual lumen tubing212, 214 of the catheter body 210. A shrink tube 222, formed ofpolyethylene terephthalate (PET) or other suitable material, surroundsthe dual-lumen tubing 212, 214 and the mandrels 216 a, 216 b. Duringmanufacture of the catheter 210, the shrink tube 222 tightens around thedual lumen tubing 212, 214 and the mandrels, 216 a, 216 b, maintainingthe position of the mandrels 216 a, 216 b adjacent the lumens 212, 214for the length of the catheter body. The shrink tube 222 extendsapproximately 10 cm past the end of the mandrels 216 a, 216 b at theproximal end of the catheter 218, to secure the shrink tube 222 aroundthe catheter body 210 and prevent the mandrels 216 a, 216 b from moving.The shrink tube 222 therefore extends from the proximal end of thecatheter 218 to a position approximately 25 cm from the distal tip 220of the aspiration catheter 210.

The distal tip of the aspiration catheter is preferably formed from 25Dto 40D PEBAX with a radiopaque filler such as BaS04. Alternatively, thedistal end of the catheter can also be provided with a soft distal tipwhich is not preformed with the tubular body, but is instead attached tothe body as a post manufacturing step. The distal tip is preferably softenough and flexible enough so as to minimize trauma to body vessels asthe catheter is advanced and to facilitate navigation of the catheter intortuous vessels, but must also be strong enough to avoid collapseduring aspiration. In one preferred embodiment, the distal tip is formedas a 0.5 cm sleeve of 25-35D PEBAX and is bonded to the tubular body byuse of an adhesive. Alternately, the distal tip may be attached to thetubular body by heat bonding, as is known to those of skill in the art.

The entire distal end of the aspiration catheter can also be attached asa separate post manufacturing step. A tubing made of polyethylene (PE),PEBAX, or polyimide can be fused to the distal end of the main bodysection of the catheter. This tubing can be from about 5 to about 60 cmin length, but is preferably around 30 cm. The distal end of theaspiration catheter can also be provided with a radiopaque material.Advantageously, radiopaque material serves as a marker 224 to help theuser position the catheter inside the patient's body as shown in FIG.13. Various well-known radiopaque materials may be used in the distalend to form the marker, such as platinum or gold. Alternatively, BaS04can be incorporated into the polymer resin itself.

FIGS. 8A, 8B, and 8C illustrate various embodiments of the distal end ofthe aspiration catheter of the present invention. FIG. 8A shows thepreferred tip 44, wherein the end has been angled and is oblique toprovide effective retrieval of particles. The angle can be from about 5degrees to about 96 degrees; an angle of about 25 degrees is preferred.This angled tip 44 is also shown in FIG. 5. This angled tip 44 maximizesthe area of aspiration. The distal tip of the aspiration catheter canalso be blunt 45, as shown in FIG. 8B, or can be tapered 46. Side ports47 can be drilled along the distal tip of the catheter to enhance theaspiration rate, as illustrated in FIGS. 8C and 2.

In another embodiment not shown, the aspiration catheter can beconfigured such that the therapy catheter can be inserted through thelumen of the aspiration catheter. The lumen is made large enough toaccommodate the desired therapy catheter. This allows the aspirationcatheter and the therapy catheter to be delivered into the patient atthe same time. When therapy is complete, the therapy catheter is removedwhile the aspiration catheter remains in place. This eliminates the needto separately deliver the aspiration catheter after removal of thetherapy catheter, saving valuable time. Alternatively, if the shaft ofthe therapy catheter is sufficiently small to allow aspiration aroundthe catheter, the therapy catheter can remain in place duringaspiration. This too saves valuable time by eliminating the need toremove the therapy catheter prior to aspirating. It is preferable thatthe size of the guide catheter used during this type of procedure besized from at least 8 to about 10 French to accommodate the size of the“over-the-therapy-catheter” aspiration catheter. Further detailsregarding aspiration and therapy catheter systems are found in copendingapplication Ser. No. 08/812,570, entitled “Catheter System for EmboliContainment”, filed Mar. 6, 1997, now U.S. Pat. No. 6,022,336, which ishereby incorporated by reference in its entirety.

In yet another embodiment, also not shown, the therapy catheter can bebuilt over the aspiration catheter. For example, a dual or triple lumencatheter having a dilatation balloon at its distal end can be used. Onelumen is used to inflate the dilatation balloon to be used forangioplasty, while the second lumen is used for aspiration. The thirdlumen is used as a guidewire lumen. Alternatively, the aspirationcatheter can be designed to deploy a stent within the occluded artery,or could include an atherectomy device on its distal end. These designsallows a single combined aspiration catheter and therapy catheter to bedelivered into the patient. When therapy is complete, aspiration iscarried out without the need to first remove the therapy catheter orseparately deliver an aspiration catheter.

As illustrated in FIG. 18, the distal end of the aspiration catheter 260may incorporate an occlusive device 262, such as an inflatable balloon.The balloon 262 is mounted on the distal end of the catheter 260, and aninflation lumen extends the length of the catheter body, from theballoon 262 to the proximal end of the catheter (not shown). Asexplained below in detail, the aspiration catheter may be used not onlyfor aspiration, but also to occlude the vessel, where desired.

The proximal end of the aspiration catheter can be fitted with a valve165, as illustrated in FIG. 12. The valve 165 allows the user toregulate the aspiration pressure. For example, a syringe can beconnected to the valve 165 and aspiration port at the proximal end ofthe catheter. With the valve 165 closed, the syringe piston can beretracted completely to provide a vacuum. The valve 165 is then openedto provide aspiration at the distal end of the aspiration catheter.Aspiration pressure can be provided in short bursts (pulsed) orcontinuously as the user desires by opening and closing the valve 165 atthe proximal end of the catheter. This valve 165 therefore providescontrol over the aspiration within the vessel. A preferred valve isavailable from Burron OEM, a division of B. Braun Medical Inc., underthe name TRAC VALVE.

The aspiration catheters of the present invention can also include acoating on the outer surface. Suitable coatings include hydrophilic,hydrophiobic, and antithrombogenic coatings, or a combination thereof.Examples of suitable coatings include heparin, silicone, polyurethaneand PVP.

The proximal end of the aspiration catheter may also include a markerwhich indicates to the physician the approximate catheter length whichcan safely and rapidly be inserted into the patient. This femoral markeris illustrated as part of the aspiration catheter 130 in FIG. 15. Thismarker 132 is placed on the aspiration catheter 130 approximately 95 cmfrom the distal tip 134 of the catheter. This length is approximatelyequal to the distance from the incision site in the femoral artery tothe ostium of the coronary artery in the average human being. Thus,during insertion of the catheter 130, the physician rapidly advances thecatheter 130 into the patient's vasculature, until the femoral marker132 near the proximal end of the catheter 136 is just outside thepatient's body. At this point, the marker 132 is an indication to thephysician to slow the insertion of the catheter 130, and to turn on thefluoroscopy to carefully deliver the distal tip of the catheter 134 tothe desired position. This therefore reduces the patient's exposure tox-rays during the procedure. The femoral marker 132 may be made of anybiocompatible material, including plastics and metals, however, anyvisible marker 132 on the outer surface of the catheter 130 may be used.

FIG. 15 illustrates another embodiment of aspiration catheter 130, whichincorporates both the femoral marker 132 described above, and a supportsheath 140. The support sheath 140 is located on the proximal end of thecatheter 136. As described above, the proximal end of the aspirationcatheter 136 may include adaptors 142 and valves. For example, commonlyused adaptors and valves include a TouhyBorst or hemostasis valve (notshown), which are positioned at the proximal end of the aspirationcatheter 136. The hemostasis valve surrounds the outer surface of theaspiration catheter 130, and tightens down around the aspirationcatheter 130 to prevent the patient's blood from flowing out around theaspiration catheter 130. As the valve is tightened, there is some riskthat the aspiration catheter 130 may be crushed. Accordingly, a supportsheath 140 may be added to the proximal end of the catheter 136 toprevent collapse or crushing of the catheter 136.

In addition, the support sheath 140 allows the aspiration catheter 130to move within the hemostasis valve. As described below, the physicianmay wish to move the distal tip of the aspiration catheter 130 in aproximal direction during aspiration, to ensure complete aspiration ofdebris. If the hemostasis valve is tightened directly onto theaspiration catheter 130, the catheter 130 is not free to slide back andforth. If the valve is tightened on the support sheath 140, however,there is a sufficient gap between the support sheath 140 and the body ofthe aspiration catheter 130 to allow for slidable movement of theaspiration catheter 130.

The support sheath 140 is preferably about 3-9 cm in length, and morepreferably is about 6 cm in length. It is positioned near the proximalend of the catheter 136, just distal to the proximal adaptor 142. Thesupport sheath 140 is preferably formed of polyimide. The sheath 140surrounds the outer surface of the aspiration catheter 130, as shown inFIG. 16, giving that portion of the aspiration catheter 120 greaterstrength and preventing the valve from crushing the aspiration lumen144.

Aspiration System

The aspiration catheter of the present invention may be used as part ofan aspiration system, as illustrated in FIG. 17. FIG. 17 illustrates asingle operator type aspiration catheter 150; over-the-wire typeaspiration catheters may, of course, also be used. The aspirationcatheter 150 is connected at its proximal end 152 to an extension line154, through use of an adaptor 153. Aspiration pressure is providedthrough the extension line 154 to the aspiration catheter 150. Theextension line 154 in turn is fitted with a valve, or stopcock 158, atits proximal end 156. This stopcock 158 controls the delivery of theaspiration pressure through the extension line 154. When the stopcock158 is in the closed position, no aspiration pressure is delivered tothe aspiration catheter 150. It is to be understood that any suitablevalve may be used to control the delivery of aspiration pressure to theaspiration catheter. As explained above, use of a valve 158 provides theuser with increased control over delivery of the aspiration pressure. Apreferred extension line and stopcock assembly is available fromMallinkrodt Medical Inc., Irvine, Calif., catalog No. 140083.

A source of aspiration pressure, such as the syringe 160 illustrated inFIG. 17, is connected to the stopcock 158. If desired, the extensionline 154 may be eliminated, and the source of aspiration pressure andthe valve 158 may be connected directly to the aspiration catheter 150.

During use, the components of the aspiration system 150, 154, 158 and160 are assembled as described above. The stopcock 158 or valve isclosed, and negative pressure is applied. In the system illustrated inFIG. 17, the plunger on the syringe 160 is retracted to provide negativepressure. To begin aspiration, the stopcock 158 is opened, whichsupplies negative pressure through the extension line 154 and down tothe distal end of the aspiration catheter 150. To stop aspiration, thestopcock 158 is closed. The stopcock 158 may be opened and closedrepeatedly to deliver the aspiration pressure in a pulsed manner ifdesired.

Additional details on various valves and syringe systems are provided incopending applications entitled “Low Profile Catheter Valve andInflation Adaptor”, Ser. No. 08/975,723, filed Nov. 20, 1997, now U.S.Pat. No. 6,050,972, “Balloon Catheter and Method of Manufacture”, Ser.No. 09/026,225, filed Feb. 19, 1998, and “Syringe and Method forInflating Low Volume Catheter Balloons”, Ser. No. 09/025,991, filed Feb.19, 1998, abandoned, all of which are hereby incorporated by referencein their entirety.

Use of the devices just described will now be explained in connectionwith the method of the present invention.

Method of the Present Invention

The method of the present invention as used to remove plaque and anyassociated thrombi from a saphenous vein graft is described below inconnection with FIG. 9. Again, it should be noted that this applicationis merely exemplary, and that the method of the present invention can beused in other blood vessels and to remove other types of occlusions aswell.

A guide catheter (not shown) is introduced into the patient'svasculature through an incision in the femoral artery in the groin ofthe patient. The guide catheter has a single large lumen, and is used toguide the insertion of other catheters and devices. The guide catheteris advanced until it reaches the aorta and the ostium of the vein graft,where it will remain in place throughout the procedure. Fluoroscopy istypically used to guide the guide catheter and other devices to thedesired location within the patient. The devices are frequently markedwith radiopaque markers to facilitate visualization of the insertion andpositioning of the devices within the patient's vasculature.

Next, a catheter or guidewire 50 having an occlusive device at itsdistal end is delivered through the guide catheter into the saphenousvein graft 5 and past the site of the occlusion 56. In this example, theocclusive device is an inflatable balloon 52. The balloon 52 is inflatedto occlude the vein graft 5 at a site distal to the occlusion 56. Theblood coming from the aorta enters the saphenous vein graft 5 and keepsany particles 58 dislodged during the procedure from flowing proximally.In addition, the blood pressure and flow coming from the aorta providesthe irrigation necessary for aspiration. As noted above, the bloodpressure in the vessel is preferably at least about 0.2 psi, and theproximal flow rate is at least about 10 cc per minute.

A therapy catheter (not shown) is then delivered, if desired. Thetherapy catheter can be any of a number of devices, including a ballooncatheter used to perform angioplasty, a catheter which delivers a stent,a catheter for delivering enzymes, chemicals, or drugs to dissolve andtreat the occlusion, an atherectomy device, a rheolitic device, or alaser or ultrasound device used to ablate the occlusion. Alternatively,the therapy catheter can be eliminated and use of the guide catheter ora separate aspiration catheter alone can be used to aspirate theocclusion. This method is especially useful to remove emboli from thecoronary arteries following acute myocardial infarction, because theaspiration catheter can be made small enough to enter the coronaryarteries.

Once the desired therapy is performed, the therapy catheter is withdrawnfrom the patient's body and an aspiration catheter 60 is delivered overthe guidewire 50 and through the guiding catheter. The aspirationcatheter 60 rides over the guidewire 50 with the guidewire 50 insertedthrough the aspiration lumen 62 of the catheter 60. Alternatively, asingle operator type aspiration catheter can be used, in which only aportion of the aspiration catheter rides over the guidewire, which isinserted into a separate guidewire lumen. FIG. 9 illustrates thetreatment site after the over-the-wire aspiration catheter 60 isinserted into the saphenous vein graft 5.

The distal tip of the aspiration catheter 64 is initially positionedclose to the occlusive balloon 52 and aspiration is begun. The operatorthen slides the aspiration catheter in a proximal direction, increasingthe distance between the distal tip 64 and the balloon 52. Aspirationcan therefore occur anywhere between about 0 to 20 cm proximal to theocclusive device. If desired, the distal tip of the aspiration catheter64 can be slidably advanced in the distal direction more than once toensure complete aspiration of all debris. As explained above, aspirationpressure can be pulsed if desired. Advantageously, the present cathetersystem and method, which uses a separate aspiration catheter that can bemoved back and forth and positioned anywhere within the blood vessels,allows the physician the flexibility to aspirate under a wide variety ofconditions and to provide aspiration in a wide variety of locationswithin the body.

The blood pressure supplied by the aorta will move any particles 58 froma position proximal to the distal tip of the aspiration catheter 64,thus allowing them to be aspirated, as illustrated by the arrows in FIG.9. If a particle, however, is too far distal to the tip of theaspiration catheter 64, the blood pressure will keep it there and notallow it to aspirated from the vessel 5. Once aspiration has begun,additional blood will flow into the area, creating turbulence andallowing for successful removal of debris.

A preferred source of negative pressure is any container containing afixed vacuum, such as a syringe, attached to the proximal end of theaspiration catheter at the aspiration port 34 (see FIGS. 5 and 17). Amechanical pump or bulb or any other appropriate source of negativepressure can also be used. Other aspiration methods, including thosewhich utilize a venturi effect, can also be used. The difference betweenthe existing pressure within the vessel and the aspiration pressurewithin the vessel should not exceed 60 psi, and more preferably, shouldnot exceed about 30 psi. If too much aspiration pressure is applied, thechange in pressure in the vessel will be too great and damage may occurto the vessel itself.

After the area inside the graft 5 just proximal to the occlusive balloon52 is aspirated to remove any particles 58 or other debris, theaspiration catheter 60 is removed. The balloon 52 is deflated and theguidewire 50 and guiding catheter are removed.

As described above, the aspiration catheter can be sized such that itcan receive the therapy catheter within its lumen, or the therapycatheter can be built over the aspiration catheter. For example, anangioplasty balloon can be attached to the distal end of the aspirationcatheter. Alternatively, the aspiration catheter can be designed todeploy a stent within the occluded artery, or could include anatherectomy device on its distal end. The aspiration catheter and thetherapy catheter are delivered over the guidewire and into the veingraft together. When therapy is complete, the therapy catheter isremoved while the aspiration catheter remains in place. Alternatively,the therapy catheter remains in place during aspiration, eliminating theneed to remove the therapy catheter prior to aspiration, which savesprecious time. When aspiration is complete, the aspiration catheter,therapy catheter, guidewire and guiding catheter are removed from thepatient's body. Delivering the aspiration catheter and therapy cathetertogether saves time, which is critical during these types of procedures.Alternatively, the guide catheter can be used to provide aspirationthrough its main lumen.

Alternative Method

An alternate method of the present invention will now be described inconnection with FIG. 18. Again, although use of the method in asaphenous vein graft is described, it should be noted that thisapplication is merely exemplary, and that the method of the presentinvention can be used in other blood vessels and to remove other typesof occlusions as well.

As described above, a guide catheter (not shown) is first introducedinto the patient's vasculature through an incision in the femoral arteryin the groin of the patient. The guide catheter has a single largelumen, and is used to guide the insertion of other catheters anddevices. The guide catheter is advanced until it reaches the aorta andthe ostium of the vein graft, where it will remain in place throughoutthe procedure. Fluoroscopy is typically used to guide the guide catheterand other devices to the desired location within the patient. Thedevices are frequently marked with radiopaque markers to facilitatevisualization of the insertion and positioning of the devices within thepatient's vasculature.

A guidewire 50 having an occlusive device on its distal end 52 and acatheter having an occlusive device on its distal end, such as theaspiration catheter 260 illustrated in FIG. 18, are delivered to aposition just proximal to the occlusion 56. The guidewire 50 andcatheter 260 can be delivered together to save time, or can be deliveredseparately. If delivered together, the guidewire 50 is inserted into themain lumen or guidewire lumen of the catheter 260, and the two aredelivered simultaneously. Once the guidewire 50 and catheter 260 are inposition proximal to the occlusion 56, the occlusion balloon 262 on theend of the catheter 260 is inflated, occluding the vessel 5. Theguidewire 50 is then advanced across the occlusion 56, until theocclusion balloon 52 is distal to the occlusion 56. The occlusionballoon 52 on the guidewire 50 is then inflated. This method isparticularly useful in saphenous vein grafts 5 where the occlusion 56tends to be friable, and there is a greater risk of dislodging particles58 which could then travel downstream.

The occlusion balloon 262 proximal to the occlusion is then deflated.The aspiration catheter 260 is then used to aspirate any loose particles58 from the area proximal to the occlusion balloon 52 positioned distalto the occlusion 56. Alternatively, if an aspiration catheter is notused to occlude the vessel, the catheter bearing the proximal occlusivedevice is removed following deactivation of the occlusive device, and aseparate aspiration catheter is delivered and used to aspirate the areaproximal to the distal occlusion balloon 52.

The aspiration catheter 260 is then removed. The occlusion balloon 52 onthe guidewire 50 remains inflated, occluding the vessel 5 at a sitedistal to the occlusion 56. As described above, therapy is thenperformed on the occlusion, the area is aspirated, the distal occlusionballoon 52 is deflated, and the guidewire 50 and guiding catheter areremoved.

While the foregoing detailed description has described severalembodiments of the apparatus and methods of the present invention, it isto be understood that the above description is illustrative only and notlimiting of the disclosed invention. It will be appreciated that thespecific dimensions of the various catheters and guidewires can differfrom those described above, and that the methods described can be usedwithin any biological conduit within the body and remain within thescope of the present invention. Thus, the invention is to be limitedonly by the claims which follow.

What is claimed is:
 1. A method for the treatment of an occlusion in ablood vessel in a patient, comprising; delivering a distal end of afirst catheter having an occlusive device on its distal end and a distalend of a second catheter having an occlusive device on its distal end toa position proximal to the occlusion; activating the occlusive device onthe first catheter to occlude the vessel proximal to the occlusion;advancing the distal end of the second catheter across the occlusion;activating the occlusive device on the second catheter to occlude thevessel distal to the occlusion; deactivating the occlusive device on thefirst catheter; and performing treatment on the occlusion afterdeactivating the occlusive device on the first catheter.
 2. The methodof claim 1, wherein the first catheter is an aspiration catheter, andthe method further comprises aspirating an area proximal to theocclusive device on the second catheter after the occlusive device onthe first catheter is deactivated and before performing treatment on theocclusion.
 3. The method of claim 1, wherein the occlusive devices areinflatable balloons and the activating steps comprise inflating theballoons.
 4. The method of claim 1, further comprising removing thefirst catheter from the patient following deactivating the occlusivedevice on the first catheter and before performing treatment on theocclusion.
 5. The method of claim 1, wherein the distal ends of thefirst catheter and the second catheter are delivered simultaneously. 6.The method of claim 4, further comprising: delivering a distal end of anaspiration catheter to a position proximal to the occlusive device onthe second catheter after removing the first catheter and beforeperforming treatment on the occlusion; and aspirating an area proximalto the occlusive device on the second catheter before performingtreatment on the occlusion.
 7. The method of claim 6, furthercompromising removing the aspiration catheter prior to performingtreatment on the occlusion.